Anthocyanins have been suggested to improve visual functions. This study examined the effect of four anthocyanins in black currant fruits on the regeneration of rhodopsin using frog rod outer segment (ROS) membranes. Cyanidin 3-glycosides, glucoside and rutinoside, stimulated the regeneration, but the corresponding delphinidins showed no significant effect. The formation of a regeneration intermediate was suggested to be accelerated by cyanidin 3-rutinoside. Their effects on the cGMP-phosphodiesterase activity in the ROS membranes were also investigated but found to be negligible. It was concluded that the major effect of anthocyanins in rod photoreceptors is on the regeneration of rhodopsin.